18th July, 1955.
Dear Dr. Kaesberg,
I was very impressed by your electron micrographs of Pea Streak Virus, published with Dr. Stahman, and naturally wondered whether enough would be available for X-ray diffraction work.  The work on TMV has progressed quite a bit since I saw you, and things have got to the stage where the best way to proceed seems to be to compare TMV with as many other rod-shaped viruses as possible.  From your micrographs, Pea Streak looks particularly promising, and if you could possibly spare a small quantity I should be extremely grateful.
I should want to use it in the form of orientated solution or gel, so, if you have any available, the most convenient form to send it in would be a rather concentrated solution or an ultra-centrifuge pellet.  With a 10 m.g. specimen one can work very comfortably, and it is, of course, possible to manage with less.
Jim Watson (of the DNA model) is back in Cambridge, and is also interested in these things, and between us we want to look at as many viruses as possible.
I shall be away during August, so it would be best not to send anything until September, when I should be able to start work at once on anything you send.
I hope things are going well with you, and that you will manage to visit us here some time.
Best wishes,
Yours sincerely,
Rosalind Franklin.